Thanks for the responses so far. Here's my "new and improved" situation in the 72 hr supplies. At this point, the idea is to keep items in one bag, and use it as a BOB if absolutely necessary.

1 Gal in my ALICE pack, along with a Nalgene and 10 Cldioxide tablets. More tabs to come in the near future, along with some coffee filters. I might stash another Nalgene in there.

2 Gallons in a very bright orange Wallyworld School backpack in my garage. The 2 bottles almost perfectly fit the main pocket. I also have 1 gal. in a milk-style container, on a shelf. I'll probably throw some food and a roll of TP in the orange bag, maybe a second pocket knife. That'll help split the location of supplies, as well as give me a quick BOB option. I can either attatch via carabiners to my external frame, throw it in the car or give to my girlfriend to carry. I've got a camo pack cover for my ALICE that can cover this bag if needed.

I assume that, in an emergency, I'll have a few minutes to grab the last bit of water from the tap. I've got my hiking supplies: a 70oz. camelback, 2 GI canteens, and 2 Nalgene bottles that are stashed. If need be, I can use my filter, jog/drive a mile to the nearest lake (or 1.5 to the next closest, with another 2 lakes within 10 miles), and top those off before the world comes crashing to a halt (people getting home from work, traffic snarling etc). I've also got a quart of H2O in my car, along with another Nalgene and 10 CL2O2 tabs (I found a store that sells them for $4).

End result, worst case scenario: 4 gallons stashed to this point, the possibility of filtering, within an hour, another 2 gallons. After that, quite a few lakes in the area, and absolute worst case scenario, the Mississippi is about 80 miles east (coming from So. Cal, this is a LOT of water!!)